This invention relates to a device for the coupled attachment of an exhaust system to an internal combustion engine or a drive assembly for improving the vibrational behavior at idle speed in which the exhaust system has an exhaust pipe system connected at each cylinder side of the motor with a catalytic converter and an upstream exhaust muffler.
One problem with internal combustion engines running in idle is vibrations developing in the drive assembly. These vibrations result in vibrations of the whole powertrain at critical engine speeds, and have an unfavorable effect on the vibrational behavior of the drive assembly at idle speed.
One object of the invention is the object of creating a device for a drive assembly, or for an internal combustion engine, which shifts the total yaw vibrations from a critical engine speed range to a non-critical low engine speed range.
This object is achieved according to the invention by providing an articulated column held in a transverse plane of the vehicle coupled with a front side of the internal combustion engine about a horizontally arranged swiveling axis aligned in a longitudinal vehicle direction. The articulated column includes, at opposite diverging brackets, mutually spaced holding devices for exhaust pipes of the exhaust system. Each of the holding devices is arranged in an exhaust pipe system between the exhaust muffler and the catalytic converter, and the exhaust muffler is connected with the internal combustion engine by way of at least one holding device. Further advantageous characteristics are apparent from dependent claims.
Through the invention, vibration adjustment of the drive assembly occurs such that the total powertrain yaw vibrations are shifted to a lower engine speed, and thus an enhanced vibrational behavior at idle speed of the drive assembly or the internal combustion engine is achieved. To achieve this, with one front side of the drive assembly or the internal combustion engine, an articulated column, held in a transverse plane of the vehicle, is coupled around a horizontally arranged swiveling axis, which is aligned in the longitudinal direction of the vehicle. At opposing divergent brackets, the articulated column exhibits holding devices, which are arranged at a distance from each other, for exhaust pipes of the exhaust system, which are each disposed in an exhaust pipe system between an exhaust muffler and the catalytic converter. The exhaust mufflers are connected with the internal combustion engine via at least one retainer with the internal combustion engine. According to the invention, the articulated column consists of a triangle-shaped support element. At free ends of the brackets, the support element has clamps or holding devices for the exhaust pipes, and in the upper area where the two supporting arms meet, a support for the horizontal swiveling axis of the articulated column is arranged at the supporting element. It is possible in this way to provide the device in a fixed connection with the drive assembly and therefore also to carry out the vibrational movements at idle speed. However, the device also is decoupled from the drive assembly, around the swiveling axis aligned horizontally and in the longitudinal direction to the powertrain, so that the device may perform movements with the exhaust mufflers and the catalytic converter directed against the movements of the drive assembly.
According to the invention, moreover, the articulated column is seated on a load bearing structure that is connected with a transverse carrier bracing of the internal combustion engine, which is supported at the vehicle structure. The holding devices for the exhaust pipes are furthermore arranged coaxially to each other according to the invention, and are at a distance in front of the articulated column. A damping effect at idle speed can be achieved by way of the fixed attachment of the exhaust pipes to the articulated column, their movement about the horizontal carrier axis, the fixed connection with the drive assembly, and the constrained movement of the exhaust pipe system, and therefore the exhaust mufflers connected thereto, as well as of the catalytic converters, which may counteract the vibrational movements of the drive assembly at idle speed with their weight and reduce the yaw mode.
Each of the exhaust pipes of the exhaust pipe system is firmly encompassed by at least one holding device of the articulated column and enters into it in a lower area of the pan of an exhaust muffler. The exhaust mufflers extend from the entry area of the exhaust pipes vertically upwards, and the center of gravity of each exhaust muffler is arranged above the holding device or devices. This particular exhaust muffler arrangement supports damping, or effects of the invention on the vibrations, at idle speed.
The internal combustion engine or the drive assembly as a whole is seated in its mounts such that it can oscillate about a vertical axis, and the articulated column oscillates against the oscillating motion of the drive assembly or the internal combustion engine about the horizontal mount axis. The exhaust mufflers counteract the oscillating motion of the drive assembly or the motor around the vertical axis at idle speed. In particular, the articulated column is coupled with the drive assembly, or the motor, and pivoted to it about the horizontal mount axis in a decoupled state. The column is simultaneously pivoted about the vertical axis in such a way that the exhaust pipes of the two exhaust pipe systems connected with the articulated column via the holding devices are opposite a movement acting on the two exhaust mufflers as well as on the catalytic converters against the oscillating motions of the drive assembly or the motor at idle speed. The fact that the two catalytic converters are connected with each other via the articulated column and pivotably at the motor or the drive assembly results in a low rigidity in vertical direction of the catalytic converters due to the pivoted arrangement, and therefore the end mufflers oscillate against the drive assembly at idle speed. Power is transmitted in the transverse direction in this way onto the drive assembly via the pivoted attachment of the articulated column.
An embodiment of the invention is shown in the drawings, and is described in more detail below.